Molecular genetic analysis of determinants defining synthesis of 2,4-diacetylphloroglucinol by Pseudomonas brassicacearum BIM B-446 bacteria.

Based on a full-sized sequence of the genome of Pseudomonas brassicacearum BIM В-446 bacteria, we determined the nucleotide sequence of the locus encoding the synthesis of the 2,4-diacetylphloroglucinol antibiotic. It was shown in the limits of a nucleotide sequence with 9087 bp size to be localized at open reading frames homologous (96-99% identical residues) to structural ( phlA, phlC, phlB, phlD, phlE, and phlI) and regulatory ( phlF, phlG, and phlH) genes of Pseudomonas brassicacearum and Pseudomonas fluorescens bacteria, which determine the production of 2,4-diacetylphloroglucinol. It emerged that closely related phl-operons differ by their environment. Thus, different genes were localized on the 3'-end. It was determined that inactivation of the phlA gene in P. brassicacearum BIM bacteria caused a loss of the ability to synthesize antibiotic and inhibited the growth of the phytopathogenic Fusarium culmorum, F. oxysporum, and Botrytis cinerea fungi; the antimicrobial activity was also decreased toward with fungal ( Alternaria alternate) and bacterial pathogens ( Pseudomonas syringae and Pectobacterium carotovorum). During inactivation of the phlF regulatory gene, which determines the synthesis of the phl-operon transcription repressor, the production of 2,4-diacetylphloroglucinol was increased. In contrast to the wild-type bacteria, phlF-mutants synthesized an antibiotic that was found in cultural liquid after 12 h of cultivation; its content reached the maximum in medium with saccharose as the carbon source. [ABSTRACT FROM AUTHOR]